The deal expands Mr. Kaulentis' share in IFOA to about 22%. That makes him IFOA's largest investor, followed by fellow co-manager Sidney Rosenberg and Stephen Gold, who merged their options order-filling group with that of Mr. Kaulentis and his partner, Maury Kravitz, to form IFOA in 1989.

Mr. Lapiana was brought into IFOA by Merc trader and former IFOA partner Lewis Borsellino. Mr.*Borsellino says he sold his IFOA stake after new Merc rules prohibited broker group principals from also trading for their own accounts.

"I offered it to the partners and they didn't want it," he says. "I sold it to Mr. Lapiana, who I've known my whole life."

Merc Chairman Emeritus Leo Melamed asserts in his recently published memoir that in the late 1980s, Mr. Sandner lied to him about his role in IFOA.

Mr. Melamed-who has since had a falling-out with Mr. Sandner-says he had appointed his former protege to a Merc reform panel in the wake of an FBI investigation of trading practices only after Mr. Sandner privately assured him he had no ties to broker associations.

Then, a new exchange rule required Mr. Sandner to disclose his IFOA stake. Mr. Melamed says Mr. Sandner apologized for having deceived him, explaining "he was afraid for his career."

Mr. Sandner last year told CRAIN'S that the events recounted by Mr. Melamed never occurred. Mr. Melamed stands by his story.

And last month, Mr. Sandner said in a statement that his IFOA stake never has influenced his duties as Merc chairman and has had a marginal effect on his futures brokerage firm, RB&H Financial Services L.P.-which he noted clears more locals than brokers.

Mr. Sandner stated that he clears less than half of IFOA's brokers. "Less than 1.5% of RB&H's gross revenues are attributed to those accounts. The notion that I have been influenced by reason of this activity is preposterous," he stated.

The decision to sell the IFOA stake capped nearly 15 months of negotiations with Mr. Kaulentis, who says he agreed to buy out Mr. Sandner in September 1995. But the two haggled over price and financing for months.

"If I'm going to buy it and take on more responsibility," Mr. Kaulentis explained before last month's sale, "then I want it at a reduced price."